Immigration and Customs Enforcement Director John Morton and Assistant U.S. Attorney Lanny A. Breuer announced the results of the ICE and FBI three-month investigation on "Cyber Monday," the day that for many shoppers kicks off the online holiday shopping season.

The government seized the domain names for the sites that sold everything from fake replica NBA jerseys to replica Louis Vuitton handbags and imitation Ugg boots.

"This is straight crime," Morton said. "This is people being duped into buying a counterfeit."

The federal government has seized the domain names of 350 websites since first targeting online counterfeiters in June 2010. Each investigation, Morton said, has grown.

Visitors to the seized domains are now greeted with a message from federal authorities explaining that the site has been seized by the government and a warning that "willful copyright infringement is a federal crime."

Morton and Breuer said while the domain names were registered in the United States most of the websites were run from abroad, primarily in China. No one has been charged with a crime in connection with the most recently seized domains. But Breuer said the investigations are ongoing.

Earlier this year five people were indicted in Virginia on conspiracy and copyright infringement charges for their roles in operating a website that the Justice Department said allowed people to illegally download high-quality movies and television shows.

Four people accused of running NinjaVideo.net have pleaded guilty. A fifth person is being sought.

It's unclear how much money the seized sites have made, or potentially cost legitimate companies. Breuer said since the crackdown on counterfeit sellers started last year, Internet users have gone to the seized domains more than 77 million times.

"Typically we don't track the volumes of sales of these particular sites," Morton said, adding that criminal organizations often hide ill-gotten profits. "It is very large figures. Well, well above millions."

Morton said it may seem like a trivial thing to buy a knock-off football jersey or look-alike sunglasses, but the profits seized by counterfeiters can help fund far more nefarious activities.

"This is increasingly not simply a matter of mom and pop violations at the corner of Fourth and Main," Morton said. "We are worried about organized crime and (that profits) are going to fuel other criminal activity."

Morton would not say if organized criminal groups are suspected of running any of the seized sites to help fund other criminal acts.